I'd recommend a meshed WiFi setup to improve your coverage. I have a Google mesh WiFi setup. The tested speed anywhere in the house is far better than my previous single-router setup. The Google router tests the speed at the connection to the cable company's modem - it's typically around 50 Mbps down (though I pay for 100 Mbps but that's another discussion). Wireless devices test between 20-30 Mbps consistently no matter where I am. With the single-router setup speeds dropped very dramatically from room to room and floor to floor. I have 30+ devices connected at any given time, including 3 Nest cameras set at their highest quality. As you know, the best throughput will be through a wire. My farthest Nest cam is about 200 feet from my house, but I have an Engenius WiFi access point about 15 feet from it (the access point is hardwired with direct bury cable). The other cameras are outside but mounted to the house and connect to the WiFi mesh points inside.
Long story longer...if your setup ever worked well but now does not I'd look for sources of wireless interference or anything that might have changed recently. If you've always had trouble I'd look into improving your WiFi coverage.
EDIT: Oh yeah - I have a Netgear WiFi extender and it sucks. Can only get 5 or 6 Mbps out of it even when it's inside the house and close to an access point.